


For Science

by breeisonfire



Series: Shutter 'verse [8]
Category: Teen Wolf (TV)
Genre: Derek's Birthday, Fluff and Angst, M/M, sterek
Language: English
Status: Completed
Published: 2014-02-06
Updated: 2014-02-06
Packaged: 2018-01-11 09:30:38
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,339
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1171461
Author URL: https://archiveofourown.org/users/breeisonfire/pseuds/breeisonfire
Summary: <blockquote class="userstuff">
              <p>It’s not until he’s at the library on a Wednesday afternoon, three weeks into their relationship, that Stiles realizes he doesn’t know Derek’s birthday.</p>
            </blockquote>





	For Science

**Author's Note:**

> Hello, friends! So Stiles and Derek are finally together, so I thought I should give you some fluff and fun to celebrate! I'm going with the fandom birthday for Derek, December 25th, and canon confuses me with Derek's age so I gave up and made him 22. By the way, in this verse, we're near the beginning of April of the pack's junior year. I don't know where everyone else's birthdays fit. The timeline is all over the place and I'm very confused, so I'm going off what makes sense in my head instead of canon.
> 
> A part of this written by my wonderful beta [whatthehale](http://archiveofourown.org/users/whatthehale) even if she doesn't want to take some credit because it was short. Enjoy!

It’s not until he’s at the library on a Wednesday afternoon, three weeks into their relationship, that Stiles realizes he doesn’t know Derek’s birthday.

Well, technically, Lydia realizes it. They were paired together in science and were planning out their experiment (and this is where he learns he and Lydia should _not_ be partners; not that they can’t get along, but they’re both bored by the high school physics curriculum and with their vast knowledge of all things dangerous, they could very well get themselves in trouble, possibly not on purpose) and talking about random things when Lydia suddenly asks, “How old is Derek exactly?”

“Twenty-one, I think,” Stiles says. “He was fifteen at the time of the fire, and that was seven years ago. Oh, twenty-two, then.”

He stops and narrows his eyes. Lydia raises an eyebrow, and says, “You don’t know Derek’s birthday, do you?”

“Do _you_?” Stiles challenges half-heartedly. In truth, he feels terrible. This is something he probably should have looked up a long time ago.

“I’m not his boyfriend,” Lydia points out, and _yeah_ , that’s right where Stiles’s thoughts are, too.

“It’s not like he’s ever shared,” Stiles says. “And I’m sure if he had been here for it, he probably would have brought it up.”

Lydia does not seem impressed by his logic. Stiles isn’t surprised. “I asked Cora and Peter how old they were once. They weren’t exactly forthcoming.”

Lydia continues giving him The Look, now with capitals because Lydia _owns_ that look. Stiles wants to sink into the floor, but says, “Fine. I’ll find out.”

An idea hits him, and he pulls out his phone. “I’ll find out right now.”

Now he’s got her attention, and hides his phone screen when she tries to look over his shoulder. He gets another look, but this one isn’t nearly as terrifying and judgemental as The Look, so he’s okay with ignoring it and pushes the call button, bringing the phone to his ear.

“Stiles, why are you calling me?” his dad answers without missing a beat. He sounds slightly worried, not that Stiles can blame him.

“I have a question,” Stiles says. “And no, it’s not illegal, and no, no one’s in trouble. Except me, possibly, because I keep getting The Look from Lydia and I think she’s going to eat me.”

That gets him a laugh from Lydia, and even his dad sounds amused when he says, “What do you want, Stiles.”

“I need to know Derek’s birthday,” Stiles says.

His dad lets out one of his patented ‘Why is my son so weird’ sighs and says, “Stiles.”

“This is for science,” Stiles tries. Then he grins and says, “Seriously, though, we need to know if werewolves go by human years or dog years. I have an invested interest in this.”

“How do you not know Derek’s birthday?” his dad asks, but he sounds interested now, so Stiles counts it as a victory.

“I’ve never thought about it before,” Stiles says. “I know he’s gotta be twenty-two by now, right?”

“Right,” his dad says, and there’s the reluctant ‘my son’s boyfriend is five years older than him’ tone. He’s been pretty cool about the entire situation, Stiles thinks, better than he’d expected, but there’s gotta be _some_ sort of resistance. Age is better than his dad focusing on the fact that Derek’s been a murder suspect twice now, so he doesn’t argue too much.

“Derek Hale,” his dad says. “Age: 22. Date of birth: December 25th.”

“His birthday is Christmas?” Stiles says in surprise. Lydia blinks in surprise, then gives him a smile. A Lydia smile, and Stiles takes a second before giving back one of his own smiles. The one Scott had used to call the ‘we’re gonna get in trouble’ smile.

Stiles needs to stop labeling everyone’s expressions. He’s going to run out of titles soon, and then where will he be?

“Christmas,” his dad confirms. “Is that all?”

“Yep,” Stiles says. “Thanks! Love-you-bye.”

He hangs up before his dad can say anything else and looks at Lydia. “So, his birthday is Christmas.”

“I heard,” Lydia says.

“What are we doing?” he places his elbows on the table and leans on them, waiting expectantly.

“Well, obviously we have to throw him a party,” Lydia says. Stiles nods, then hesitates.

“Nothing too big,” he says. “Just the pack, and our parents. And maybe Danny, and some of his friends from the station. Too many people will make Derek uncomfortable.”

Lydia nods, and Stiles lets out a breath. “Alright. What are we doing for our science project?”

\------------------------------------------------------------------------------------------

Derek knows the others are up to something. He’s not blind. It’s true that the pack’s gotten better at hiding secrets, but Derek knows them all, and he knows the innocent look Isaac has on his face and the somewhat guilty look on Scott’s means they’re planning something and not including him. Allison’s carefully neutral, so Derek’s suspicious of her, as well. Lydia’s acting normal, but she’s spending a lot of time with Stiles, who is almost always up to something, and Derek’s fairly certain science isn’t the only thing going on there. For one, science doesn’t involve cake (although knowing Lydia and Stiles, there’s a possibility it _does_ , in which case Derek really doesn’t want to know).

He feels somewhat left out, but no one’s panicking, and in fact this secret seems to make everyone feel happier for reasons Derek doesn’t understand, so he’s not too concerned yet. And in any case, Stiles doesn’t act any different on their date, when they go out for ice cream and Stiles tells the story of kickball in P.E. He’s totally animated, and ends up getting ice cream on his forehead, which he doesn’t notice, and Derek has to take a picture, because he can’t stop laughing. And then he sends it to Scott, to add to the slowly growing Pack Scrapbook Extraordinaire (they have got to stop letting Stiles name things).

So, on Thursday, when Stiles randomly texts him asking if he wants to do something because he’s bored, Derek agrees, even if he feels slightly suspicious. He’s even more so when Stiles insists on going out somewhere, because they’ve spent plenty nights just watching movies in his apartment.

He lets Stiles drive this time, because Stiles loves his Jeep, even if no one else does, and it lets Derek focus on other things, like the fact that his EMT training course starts in a couple weeks and how long it’s been since he’s had to do homework. He lets Stiles’s rambling wash over him as they head to the deli. It’s still one of Derek’s favorites, and Stiles loves it, so they go there quite a bit.

Derek waits until they’re sitting down and both eating before he cracks. “So what the hell is going on?”

“What?” Stiles asks, the picture of pure innocence. Derek wonders vaguely how the sheriff is still somewhat sane, because Stiles can be a real pain in the ass when he knows something and won’t give it up, even when he’s a really bad liar.

“Why is everyone going around with the delusion that they’re sneaky?” he deadpans. Stiles snorts.

“They’re so bad at it,” he agrees.

“You are, too,” Derek points out.

“Well, _yeah_ , but it’s normal for me to be like this,” Stiles says. “So no one’s suspicious. You already know I’m up to something, if no one else was involved you wouldn’t be suspicious.”

Which is a fair point. “So your strategy is the boy who cried wolf reversed.”

“Why are wolves used in symbolism so much?” Stiles asks, his mind apparently going a completely different direction than Derek’s. It’s something he’s used to by now, but the topics sometimes catch him by surprise. At least he can see the connection this time.

“Probably has something to do with their role in mythology,” he says, and that sends Stiles on a rundown of wolf mythology. Derek adds what he knows from what he’d been taught by his family, and by the time they get back out to the car, Derek realizes that Stiles never answered his question and glares at him.

“Don’t do that,” he says.

“Do what?” now Stiles really is confused.

“Distract me,” Derek says. “What’s going on?”

“No one’s in trouble,” Stiles says. “It’s not a bad thing. It’s a surprise. For you. So I can’t tell you.”

That shuts Derek up. A surprise for him. He doesn’t have the slightest idea what it could be. Or why. His birthday was months ago, and Derek doesn’t think he’s ever mentioned it to anyone. Although he supposes Stiles could have asked Cora or his dad. Either one would have been able to tell him.

He really doesn’t have any idea what it could be, and thinks hard about it as Stiles pulls into the parking lot of the movie theater, and they go see a movie Stiles has been wanting to see. Derek’s not particularly interested in the movie, and distracts himself throughout it by messing with Stiles’s hand. Stiles doesn’t seem to mind, even if he doesn’t pay much attention to Derek, too caught up in the movie.

After the movie, Stiles is checking his phone every five seconds, and he seems to be bursting with excitement. Derek’s almost afraid to ask, but before he can, Stiles’s phone vibrates, and Stiles’s eyes light up as he reads it.

“Alright!” he says brightly. “Back to your apartment!”

“What?” Derek blinks, completely confused. “Why my apartment? Did you guys break into my apartment?”

“Not breaking in if we have a key,” Stiles points out.

“I’m going to break all of those keys,” Derek mumbles as he’s pulled out of the theater. He’s too curious to be bothered by this news, and they’re _pack_ anyway, so he supposes they’ve got a good reason to take over his apartment. As long as no one’s dead, or hurt, or being ritually sacrificed, or drunk, or high. He’s got a couple of lines they can’t cross.

He doesn’t ask as they get to the apartment building, but he does glance around the parking lot, and spots several cars he knows. Lydia and Allison’s are both parked by Derek’s Camaro. Scott’s bike is parked next to the space Stiles parks in, and the McCall’s car is on the other side of that. And one row over, a police cruiser Derek recognizes as Sheriff Stilinski’s is parked. He doesn’t have a clue what’s going on.

He’s still being pulled by Stiles as they get to the stairs, and waves at Nate, his landlord, as he’s dragged up them. Nate waves back, his usual easygoing smile on his face, and at least Derek’s reassured no one’s blown up his apartment while he was gone. Not that he’d actually assumed that (okay, yes he had, because he knows Lydia has the skills, Allison has the resources, and Stiles has the impulsiveness, and the fact that Stiles has been with him all afternoon proves absolutely nothing).

He listens closely as they get to his floor, and Derek hears quiet voices, all of which he recognizes. He’s surprised when he hears some of his friends from the fire station, predominantly the fire chief, Brian. He directs his surprised face to Stiles, who hums innocently as he unlocks the door.

The door opens to a small group of people in his living room, and he blinks as they all turn to him.

“Surprise!” Scott says. He’s echoed by the other members of the pack, except Stiles, who is too busy grinning widely at him.

“What?” is all Derek can say, because that’s all he’s thinking.

“We missed your birthday,” Lydia says, and the tone of her voice tells Derek she is not happy about that. “So we had to make up for it. Obviously.”

“Obviously,” Derek mutters sarcastically, because he does not understand the way their heads work. But he’s not about to argue, because it’s been a very long time since he’s had a birthday party, and from the way the apartment works and smells, they’ve worked hard on this. So he just grins.

As if that’s some sort of cue, the atmosphere immediately relaxes, and Stiles steers him to the couch and pushes him down to sit.

“Stay,” he says, then disappears into the kitchen. Derek watches after him for a second, before he’s distracted by Cassie, one of his friends from the station. She’s grinning, and sits down next to him.

“Hi,” Derek says, somewhat surprised.

“Hi,” she says. “That boyfriend of yours is certainly persistent.”

Derek snorts, because that is an understatement, but he nods. “Yeah.”

“But cute,” Cassie continues. “I’m glad he invited me, because I didn’t know your birthday. Was it some big secret?”

“Not on purpose,” Derek says, cursing his social skills. He’s pretty good when it’s just the pack, but he’s still learning to deal with people outside the pack.

Speaking of outside the pack, as Cassie gets distracted and gets up, Danny sits down next to him and says immediately, “So you’re not Miguel, huh?”

Derek blinks for a second before he remembers what Danny’s talking about and feels his ears go red. He shakes his head.

“I knew it,” Danny says casually. “Stiles doesn’t exactly give off straight vibes, and besides, his family is Polish. I don’t know who he thought he was kidding.”

“Nobody,” Derek says. “He thinks if he’s obvious about it, it’s him telling you to back off without actually saying it.”

Danny laughs. “That makes sense in a Stiles kind of way. Happy birthday. Or you know, happy really late birthday.”

Derek gives Danny a smile and says, “Thanks.”

Stiles comes out just then, leading Isaac, who’s carrying a cake. There are lit candles on it, and Derek stares as Isaac stops in front of him and Stiles starts singing Happy Birthday. Derek resists the urge to throw on of the couch pillows at Stiles’s face as the rest of the room joins in, and focuses on the candles, which are all blue. They match the color his eyes go when he’s shifted, and he knows that’s not a coincidence.

They finish the song and Derek blows out the candles under threat of having his face shoved into the cake if he resists, and then Isaac sets the cake down on the dining table. Stiles makes Derek sit at the table, and when there’s a knock at the door, doesn’t let him get up.

Derek listens curiously to Stiles answering the door as he accepts the piece of cake and scoops of ice cream given to him by the sheriff and Melissa. He can’t think of anyone else who should be at the party.

“Hey, you made it!” Stiles sounds really excited, and Derek turns to see who it is, but he hears it first and whips around entirely.

“Of course I made it, it’s my brother’s birthday party,” Cora says and Derek stares in surprise as he sees her.

“Cora!” Isaac says. Derek gets up and goes over to her, pulling her into a hug. He hadn’t realized how much he’d missed her over the past couple of months, but it’s really good to see her, and he’s really glad they invited her.

Stiles makes Cora sit next to Derek, and then bounces away, doing God-knows-what. Derek eats cake and talks with Cora and the others at the table. After a while, he gets tired of talking, and just observes the others at the table. Isaac’s talking to Cora about _Pacific Rim_ , and they’re both really into it. Danny and Scott are talking about lacrosse and measuring their chances of winning championships this year. Melissa and John are talking quietly, and Derek decides not to eavesdrop on that one. The fire chief is talking to Allison about his travels (apparently he’d done quite a bit of traveling when he was younger). At some point, Nate had come up and joined the party, and he’s talking to Cassie about cars. Derek doesn’t know where Stiles and Lydia went to, but he’s feeling pretty content.

He’s finished his cake and ice cream and is about to get up to find Stiles when Lydia comes up on his other side and plops a box down in front of Derek.

“Gift time!” she says. Derek blinks.

“Gift?” he repeats, and he sees Stiles heading toward him holding several boxes. They’d gotten him _presents_. Derek’s not sure how he feels about that.

“Open that one,” Lydia says impatiently, and points to the one in front of him. Derek stares at it and then, knowing he’d lose any argument he’d made, he opened it. He sees it’s from Lydia, and holds his breath as he opens it. Then he looks up, confused.

“New shoes?” he says. Not upset, not at all, just surprised that Lydia would think to buy that for him.

“Your old shoes are falling apart,” Lydia says. “Don’t argue.”

“Wasn’t going to,” Derek says, and then grins. “Thanks.”

Lydia gives him a smile in return, and then Scott says, “My turn!” and passes him a box that’s heavier than the last one. He raises an eyebrow, and opens it to see all three _Hunger Games_ books.

“You still have Stiles’s,” Scott says when Derek raises an eyebrow at him. “I figured you should have your own copies.”

Derek thanks him, too, and then takes the card Allison passes him. It’s got a $50 gift card for Barnes and Noble, and he gives her a real smile. He gets one in return, the first one he’d ever gotten, and can’t help but feel sort of triumphant about that.

Then she passes him another card. “From my dad. Kind of an apology.”

Derek takes it and opens it to see a gift card to the deli, and has to cover his mouth before he laughs out loud. Once he’s sure he’s calm, he takes his hand off and says, “Tell him thanks.”

Allison nods. Isaac hands him a CD case, which he sees is a mixed CD. Isaac’s taken wolf-themed songs and put them on a CD, and Derek laughs at that, too, before handing it to Stiles, because he know he’ll find that hilarious. Stiles cracks up and Cora takes it from him to read it too before high-fiving Isaac.

He gets a camera from Melissa and John, and Danny’s got him some art supplies (which he glares at each member of the pack for, because that was supposed to be a secret; he’s fairly certain from the way Scott reacts that it’s his fault). Cassie and the other fire station workers have bought him a set of the _Lord of the Rings_ books. Brian passes him an unwrapped sketchpad.

Cora hands him a stack of postcards, and he grins. When they’d been driving around on their long road trip, they’d started collecting the most ridiculous post cards they could fine. Apparently Cora had done that on her way to Beacon Hills.

It takes a couple minutes, but Derek realizes Stiles hasn’t given him anything, and finds that immediately suspicious. He narrows his eyes at Stiles, who just smiles mischievously. Derek concludes he doesn’t want to know.

The party starts to wind down after that. Cassie and the others have to leave, and Brian has to go to the station. John gets a call from his deputy and has to go, and Melissa has a shift at the hospital. Nate follows them out, thanking them for letting him crash the party. That leaves the pack and Cora. She’s staying the night at his apartment before driving home the next day, so he knows she isn’t leaving, but the pack has school the next day. He doesn’t point this out, because he knows they already know, but he does give them a curious look. Scott just shrugs.

“Stiles didn’t tell anybody what he got you,” he says. “We’re curious.”

“I know,” Cora says, and Stiles shoots her a glare. Derek’s _really_ curious now, and wonders what the hell Stiles got him that only Cora knows about.

Now everyone’s staring Stiles down, and he finally groans and says, “Fine! I was hoping it would be more private, you all suck.”

He leaves the room and goes back to the second bedroom. He comes back after a few minutes, holding what looks like a giant book wrapped in newspaper. He hands it to Derek.

“I had a lot of help on it,” he says. “Cora, my dad, Melissa, Deaton, I would have made Peter help, too, but he’s never around when I actually want him to be.”

Derek snorts, then unwraps the paper. Once it’s gone, he sees he’s holding a scrapbook, and he raises an eyebrow at Stiles.

“Don’t give me that look, open it,” Stiles says, a guarded look on his face. Derek doesn’t know what that’s about, and turns his attention back to the scrapbook, opening it to the first page.

He stares at the picture there. It’s a picture of the full Hale family, one taken what looks like weeks before the fire. It’s a full picture, one he remembers hanging in the hallway at the top of the stairs. He’d thought it had burned.

Stiles clears his throat and says, “There’s more.”

Derek turns the page, somewhat eagerly, and sees a picture of his mom, taking up most of the page. He remembered it, too. His mom had been a lawyer, and a good one, so she’d been in the paper quite a few times. Stiles had apparently taken to hunting them down.

That’s what it is. Page after page of any and all pictures Stiles had been able to get his hands on, some of them obviously retouched but, not too much. And the further he gets into the book, the more recent things are, until he starts seeing pictures of his current pack, from when he’d first come back to a few days previous.

It’s a full minute before he’s able to say anything, and all he can get out is, “Thank you.”

He doesn’t look up, not trusting himself to keep it together if he does look, so he stares at the last picture, one of the entire pack after an impromptu dinner, the Monday after he and Stiles had gone on their first date. Melissa and John had been there, since they’d been at the Stilinski house, and Melissa had demanded a picture of the group, so they’d all piled onto the couch, and after arguing which one of them was going to sit on the floor, because they didn’t all fit, Stiles had just plopped down on Derek’s lap, spreading his legs over the rest of the pack. Everyone had been surprised, and Melissa had taken the picture before any of them except Stiles knew what was going on. It’s one of Derek’s favorite pictures.

“Scott gave me the idea with his whole pack scrapbook thing,” Stiles says. “And then I enlisted my dad, and started talking to Cora, and Deaton somehow heard about it and had some resources, and Melissa had a _ton_ of old newspapers in their basement, so I raided it all. Some of the pictures were old, so I had to fix them on the computer, and that first picture is a copy of the one Cora has, not the original, but, you know, it works.”

Before Derek can say anything, Scott speaks up. “I think I’m gonna go now. You coming, Isaac?”

“Yeah,” Isaac says, and follows Scott out.

“See you,” Allison says, taking the hint.

“Stiles, that means you’re stuck on clean up,” Lydia says as she leaves.

“Of course it does,” Stiles says.

“I’ll be in the other room,” Cora says, and leaves.

“So fucking subtle,” Stiles mutters. Derek grabs his arm and pulls him down on the couch next to him.

“Thank you,” he says sincerely, and pulls Stiles into a kiss.

He can tell Stiles is distracted though, and is proved correct when Stiles fumbles for his phone _while they’re kissing_. He pulls back, wondering what his boyfriend is up to when Stiles takes a shot of them with his Snapchat app.

Derek looks at the screen while Stiles types out a message and sees both he and Stiles look _happy_ and flushed and rolls his eyes at the message: ‘the present was a success!’

His boyfriend is truly ridiculous. Stiles grins and kisses him again, obviously concentrating a bit more this time given how the kiss turns slightly dirty towards the end.

“Wait,” Stiles says, before pulling back _again_. Derek makes an annoyed noise. “There’s more.”

“What?” Derek blinks, not sure he can handle more. “How is there _more_?”

“Well, it’s not as impressive,” Stiles says, and pulls something out of his pocket. He hands it to Derek.

It’s a key, and Derek is confused for a second before it hits him. “A key to your house. Really.”

“Hey, I have one to yours,” Stiles says. “And besides, my dad doesn’t want you coming through the window. Something about the neighbors could see and call the cops, and wouldn’t that be embarrassing. The sheriff called to his own house because his son’s boyfriend doesn’t use the front door.”

Derek snorts despite himself and puts the key in his pocket. “I may forget I have it and come through the window anyway.”

“At least now I can say I tried,” Stiles says, wiggling his eyebrows, and Derek rolls his eyes. Stiles smirks, then frowns and says, “I really do have to clean up, though.”

Derek grins and says, “Too bad it’s almost eleven. I’d say let’s listen to Isaac’s new playlist.”

Stiles laughs and stands up. He pauses and turns to Derek. “We should experiment. How hard is it to kiss and clean at the same time?”

“No,” Derek says, spreading out on the couch and opening the scrapbook again, ignoring his annoyed boyfriend’s exclamation.

“But it’s for _science_!”


End file.
